The present invention relates to a flexible cable support and guide device for safely and surely supporting and guiding electric cables, optical fiber cables, liquid supply hoses or the like flexible cables used for feeding energy, such as electric power or working fluid, to machine tools, electronic equipment, industrial robots, conveyance machines or movable parts thereof.
Cable support and guide devices for holding therein cables used to feed electric power or working fluid to a movable part of a machine or a mobile machine are known as disclosed for example in Japanese Patent Publication No. HEI-2-40135 and Japanese Patent Laid-open Publication No. HEI-10-28310.
The cable support and guide device shown in Japanese Patent Publication No. HEI-2-40135 is comprised of a series of U-shaped chain elements articulately connected together to form a flexible chain. The U-shaped chain elements each have two opposed link plates formed as an integral part of each chain element, and a pair of laterally projecting pivot pins and a pair of aligned pin-accommodating holes formed at opposite longitudinal end portions of the link plates. The pivot pins of one chain element are fitted in the pin-accommodating holes of the adjacent chain element so that the chain elements are pivotally movable about the pivot pins. Each chain element further has a cover strip hinged at one end to the upper end of one link plate, the other end of the cover strip being releasably engaged with the upper end of the other link plate so that cables received in the chain are prevented from displacing off the chain.
The cable support and guide device shown in Japanese Patent Laid-open Publication No. HEI-10-28310 has a hollow body molded of synthetic resin and including an elongated bottom wall and two opposed side walls formed integrally with opposite longitudinal edges of the bottom wall. The side walls are segmented into side wall pieces arranged longitudinally of the hollow body so that the bottom wall of the hollow body is flexibly bendable. One side wall has an integral end elongation resiliently bendable to form a top wall of the hollow body, the end elongation being releasably engaged with the upper end of the other side wall. As an alternative, a number of top covers may be removably attached to the upper ends of the side plates. The hollow body further has a series of trapezoidal fins formed on the under surface of the bottom wall along the length of the bottom wall. When the hollow body is bent or flexed, adjacent oblique sides of the trapezoidal fins come into abutment with each other to thereby limit the angle of bend of the hollow body of the chain support and guide device.
The cable support and guide device disclosed in Japanese Patent Publication No. HEI-2-40135 has a problem that the structure is likely to sag under the weight of the cables accommodated in the cable support and guide device. To deal with this problem, an attempt has been made to initially form the cable support and guide device into an upwardly curved bow-like configuration such that, when loaded (i.e., when cables are placed therein), the upwardly curved cable support and guide device assumes a flattened configuration. However, due to its initial bow-like configuration, the cable support and guide device requires a relatively large vertical space for installation thereof. In use, the cable support and guide device is pushed and pulled to slide along a traveling path and hence is subjected to a relatively large frictional resistance against movement thereof. As a consequence, repeated use of the cable support and guide device would cause deformation of the pivot pins, pin-receiving holes and tilt-angle limiting stoppers of the chain elements due to wear or fatigue. This may result in accidental separation of the chain elements, making the cable support and guide device inoperative as a whole.
The cable support and guide device disclosed in Japanese Patent Laid-open Publication No. HEI-10-28310 also has a problem that due to its resiliently deformable molded structure, the hollow is likely to buckle at a curved or bent portion thereof when subjected to a heavy load applied from the above, thus failing to maintain an accurate radius of curvature of the bent portion. Further, the hollow body molded of synthetic resin is susceptible to distortion, is difficult to support heavy cables, is likely to become unstable and cause twisting when weight of the cables is unevenly distributed, may create a sag when traveling along a long straight path, and tends to tilt due to insufficient rigidity when traveling along a curved path.
It is accordingly an object of the present invention to provide a flexible cable support and guide device having structural features which are able to prevent distortion or twisting of the cable support and guide device from occurring not only when the device is in a stationary state on a horizontal path with cables accommodated therein, but also when the device is achieving a relatively long stroke of travel.
Another object of the present invention is to provide a flexible cable support and guide device which is easily drivable and capable of moving smoothly without creating undue frictional resistance.
To achieve the foregoing objects, according to the present invention, there is provided a flexible cable support and guide device comprising a pair of pulleys rotatably supported on opposite ends of a support rod, and a movable cable holder wound around the pulleys. The movable cable holder includes a looped belt trained around the pulleys, a pair of flexible tubes carried on an outer circumferential surface of the belt with ends of the two tubes confronting each other mutually, the tubes accommodating within them cables, and a movable end formed jointly by one pair of mutually confronting ends of the two tubes, and a fixed end formed jointly by the other pair of mutually confronting ends of the two tubes. The cables are pulled out from the movable end of the cable holder for connection to a mobile machine or a movable machine part, and the cables are also pulled out from the fixed end of the cable holder for connection to a fixed external power source.
In one form of the present invention, the pulleys have a flat outer circumferential surface, and the belt comprises a flat belt.
In another form of the present invention, the pulleys comprise toothed pulleys each having evenly spaced teeth on an outer circumferential surface thereof, and the belt comprises a toothed belt having evenly spaced teeth on an inner circumferential surface thereof for mesh with the teeth of the toothed pulleys.
Preferably, the flexible tubes comprise a corrugated tube. The flexible tubes may be made of rubber or molded of synthetic resin. The flexible tubes may be attached by bonding to the outer circumferential surface of the looped belt.
The flexible support and guide device may further comprise a plurality of fasteners detachably connected to the belt to attach the flexible tubes to the outer circumferential surface of the belt. In one preferred form, the belt has a pair of side flanges formed on the outer circumferential surface of the belt and extending along opposite longitudinal edges of the belt, and a plurality of pairs of aligned retaining holes formed in the side flanges and spaced at equal intervals in the longitudinal direction of the belt. The fasteners each comprise a U-shaped fastener strip formed from a resilient material and having a pair of locking pins projecting laterally and outwardly from distal ends of two legs of the U-shaped fastener strip. The locking pins are received in one pair of aligned retaining holes to attach the fastener strip to the belt with the flexible tubes held between the belt and the fastener strip. The side flanges may be provided with a number of transverse slits formed therein at equal intervals in the longitudinal direction of the side flanges.
With the cable support and guide device thus constructed, when one of the pulleys is driven in rotation, the cable holder travels in one or the opposite direction. At the same time, the cable support and guide device itself moves along guide rails installed on a floor surface, for example. In this instance, the fixed end of the cable holder remains stationary while the movable end of the cable holder moves together with the mobile machine or the movable machine part.